Molec. bio

Molec. bio - Zoology 470 2009 Course handouts Page 9...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Zoology 470 – 2009 – Course handouts Page 9 Molecular Techniques in Developmental Biology Big idea: DNA encodes RNA, which, after appropriate processing, produces a messenger RNA (mRNA). mRNAs in turn are translated into proteins. Thus by working with DNA, we are working with information required to make a protein. DNA is a very stable molecule that has convenient properties we can take advantage of. RNA, on the other hand, is highly unstable, and tends to degrade rapidly, and proteins can only be studied biochemically. Molecular biology is the powerful technology that allows us to work with DNA (and RNA and proteins), using a number of different techniques. Electrophoresis Big idea : Separate proteins or nucleic acids (DNA, RNA) by size by driving them through a gel (made of a polymer, like polyacrylamide , or a gel, like agarose ). Why do this? Since DNA and RNA are made of four simple building blocks in long chains, we can’t tell them apart chemically. It’s the number of bases and their order that matters. This technique at least allows us to distinguish different DNAs or RNAs by size , if not by the sequence of the bases they contain. Campbell, 5e, Fig. 17.3
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Zoology 470 – 2009 – Course handouts Page 10 Nucleic Acid Hybridization Big idea : Remember that DNA can undergo base pairing with a complementary strand of DNA, or with a complementary strand of RNA; this process is essential for replication and transcription. However, largely complementary sequences can do this, too. Furthermore, this process is reversible; heating up a solution of nucleic in the presence of low salt tends to cause complementary sequences to fall apart ( “melt” ); whereas lower temperatures and higher salt solutions allow them to stick together ( “hybridize” , or “anneal” ). Even if the nucleic acid we want to detect is immobilized in a fixed cell or on a membrane, we can still make use of this key property. In that case, the sequence we use to hybridize to the membrane or tissue is called a probe . see Purves et al., 4e, Fig. 13.1 DNA Cloning Big idea : We want to get DNA in a form that is useful for making lots of it. To do this, we chop the DNA with a restriction enzyme , producing sticky ends , and then we ligate the sticky DNA into a vector (a piece of bacterial or yeast DNA that has been similarly rended sticky). Then we let bacteria do all the work of making this new DNA for us. In a variation of this technique, we first take mRNA and make complementary, or cDNA , by using an enzyme called reverse transcriptase . Then we make this single stranded DNA double stranded, and then we clone this DNA. See Campbell, 5e, Fig. 20.2
Background image of page 2
Zoology 470 – 2009 – Course handouts Page 11 DNA Libraries Big idea : We need a way to study genes outside the animal (after all, genes are pretty small!). One way to do this is to make a “library” of DNA by taking a big mixture of DNA, chopping it up, and putting it into a vector (DNA from something like a bacterium or a bacterial virus - called a phage- that allows us to make lots of
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2009 for the course ZOO 470 taught by Professor Hardin during the Spring '08 term at Wisconsin.

Page1 / 13

Molec. bio - Zoology 470 2009 Course handouts Page 9...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online